A screen printing machine is for moving a squeegee by a squeegee moving device along a mask to print a printable material on a printing object through a through hole of the mask. This screen printing machine is widely used for printing solder cream (hereinafter abbreviated as “solder” unless otherwise required) on a circuit substrate, and Patent Document 1 below discloses one example of this machine, for which user's demands are stiff as compared to a general screen printing machine. For example, the solder needs to be printed extremely precisely on a pad formed on the circuit substrate. Thus, as described in Patent Document 1, fiducial marks are provided respectively on the circuit substrate and the mask, and an imaging device is moved into a space between the circuit substrate and the mask in a state in which the circuit substrate and the mask are spaced apart from each other. In this state, the imaging device takes images of the fiducial marks of the circuit substrate and the mask, for example, to detect a relative positional error of the circuit substrate and the mask, and based on the detection a position of the circuit substrate or the mask is adjusted.
As described in Patent Document 1, the position of the circuit substrate is conventionally adjusted by moving a substrate support device supporting the circuit substrate, in a right and left direction and a front and rear direction perpendicular to each other in a horizontal plane and by rotating the substrate support device about its vertical rotation axis, while a position of the mask, as described in Patent Document 1, is conventionally adjusted by moving and rotating a mask frame supporting the mask with respect to a mask frame receiver. In these techniques, however, there is still room for improvements as described below.